Serotonin (5-HT) is both a central neurotransmitter and vasoactive agent. This monoamine exerts a wide range of metabolic and vascular effects on the cerebral circulation so it may well be involved in the mechanisms that link neuronal activity to cerebral blood flow. Recently, we had demonstrated that the changes in the cerebral cortical content of 5-HT, its precursor tryptophan and its main metabolite 5-hydroxyindole acetic acid, unlike those of energy metabolites, depend on the age of the animal and the duration of ischemia. To shed some more light on this phenomenon, we studied the effect of ischemia on synaptosomal uptake and release of 5-HT in cerebral cortex, hippocampus and striatum of young and adult gerbils. The findings indicated that the same ischemic insult affected differently the synaptosomal uptake and release of 5-HT in all examined brain structures (except for the cortical 5-HT uptake) of the young and adult brain. Moreover, the observed regional differences in synaptosomal uptake and release in the brain of both young and adult animals may represent one of the factors responsible for selective vulnerability of ischemic injury.